A Framework for Annotating Information Structure in Discourse

Proceedings of the Workshop on Frontiers in Corpus Annotation II: Pie in the Sky, pages 45–52, Ann Arbor, June 2005. c⃝2005 Association for Computational Linguistics A Framework for Annotating Information Structure in Discourse Sasha Calhoun � , Malvina Nissim � , Mark Steedman � and Jason Brenier � � Institute for Communicating and Collaborative Systems, University of Edinburgh, UK Sasha.Calhoun@ed.ac.uk, � steedman,mnissim � @inf.ed.ac.uk � Department of Linguistics, University of Colorado at Boulder jbrenier@colorado.edu Abstract We present a framework for the integrated analysis of the textual and prosodic char- acteristics of information structure in the Switchboard corpus of conversational En- glish. Information structure describes the availability, organisation and salience of entities in a discourse model. We present standards for the annotation of informa- tion status (old, mediated and new), and give guidelines for annotating informa- tion structure, i.e. theme/rheme and back- ground/kontrast. We show that informa- tion structure in English can only be anal- ysed concurrently with prosodic promi- nence and phrasing. This annotation, us- ing stand-off XML in NXT, can help es- tablish standards for the annotation of in- formation structure in discourse. 1 Introduction We present a framework for the integrated analysis of the textual and prosodic characteristics of infor- mation structure in a corpus of conversational En- glish. Section 2 introduces the corpus as well as the tools we employ in the annotation process. We pro- pose two complementary annotation efforts within this framework. The first, information status (old, mediated, new), expresses the availability of entities in discourse (Section 3). The second scheme will firstly annotate theme/rheme, i.e. how each intona- tion phrase is organised in the discourse model, and secondly kontrast: how salient the speaker wishes to make each entity, property or relation (Section 4). We will demonstrate that the perception of both of these is intimately affected by prosodic structure. In particular, the theme/rheme division affects prosodic phrasing; and information status and kontrast affect relative prosodic prominence. Therefore we also propose to annotate a subset of the corpus for this prosodic information (Section 5). In conjunction with existing annotations of the corpus, our inte- grated framework using NXT will be unique in the field of conversational speech in terms of size and richness of annotation. 2 Corpus and Tools The Switchboard Corpus (Godfrey et al., 1992) con- sists of 2430 spontaneous phone conversations (av- erage six minutes), between speakers of American English, for three million words. The corpus is distributed as stereo speech signals with an ortho- graphic transcription per channel time-stamped at the word level. A third of this is syntactically parsed as part of the Penn Treebank (Marcus et al., 1993) and has dialog act annotation (Shriberg et al., 1998). We used a subset of this. In adherence with current standards, we converted all the existing annotations, and are producing the new discourse annotations in a coherent multi-layered XML-conformant schema, using NXT technology (Carletta et al., 2004).1 This allows us to search over and integrate information from the many layers of annotation, including …

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